Aerobic Composting Of Landfill Sludge With Different C/N Ratios Based On Conditioning Of Forestry Wastes

Aerobic composting is one of the common technologies to realize sludge resource utilization.Appropriate initial composting conditions are the premise and foundation for the successful preparation of sludge for landscaping.After 54 days of aerobic composting,the contents of nitrate nitrogen,ammonium nitrogen,total phosphorus,available phosphorus,total potassium,available potassium and other nutrient elements,as well as the forms of heavy metals Cu,Zn and bioavailability content of the materials were studied under different C/N ratios,At the same time,the effects of Inoculants on microbial community diversity in different C/N ratios were explored.The main results are as follows:1.Aerobic composting can be divided into three stages: warming stage,moderate temperature stage and cooling stage.It is moderate temperature aerobic composting.The significant difference of temperature is limited to 54 days(P = 0);after composting,the p H values of C/N20(T1),C/N25(T2)and C/N30(T3)were 6.04,5.95 and 5.79,and the conductivity values were 1.42,1.15 and 1.21 ms·cm-1,respectively;The final contents of ammonium nitrogen,nitrate nitrogen,available phosphorus and available potassium were0.28,0.21 and 0.26 g·kg-1,0.28,0.21 and 0.26 g·kg-1,2.01,1.94 and 1.86 g·kg-1,2.35,1.21 and 1.35 g·kg-1,respectively.2.Effects on speciation of heavy metals Cu and Zn.The sum of acetic acid soluble state and reducible state of Cu increased from 32%,38% and 40% to 72%,74% and 74% respectively,and the acetic acid soluble state and reducible state of Zn increased from 84%,85% and 86% to 96%,98% and 97%respectively.3.The effect on seed germination index.After composting,all treatment groups had no toxicity to plant growth.When the ratio of carbon to nitrogen was 25,the highest germination rate of sludge seed index was 186%,and the lowest toxicity to plant growth.4.The difference of species composition of bacteria and fungi.In the composting process with different C/N ratios,the bacterial species composition was basically the same,and the community structure was different.The difference between C/N ratio 20 and C/N ratio 25 was small,and the difference between C/N ratio 30 was large;When the C/N ratio was 25,the fungal community structure was close to that of 20 in the early stage,and similar to that of 20 in the later stage.5.The difference between alpha diversity and beta diversity.Alpha diversity analysis showed that the richness and diversity of bacteria and fungi were higher when C/N ratio was 20 and 25 than when C/N ratio was 30;The results of beta diversity analysis showed that the similarity of bacterial and fungal communities was higher when the C/N ratio was 20 and 25,and the difference was larger when the C/N ratio was 30.